JS 获取元素距离body的偏移量

 // 获取元素距离BODY的偏移量
    const offset = function offset(element) {
        let parent = element.offsetParent,
            top = element.offsetTop,
            left = element.offsetLeft;
        while (parent) {
            if (!/MSIE 8/.test(navigator.userAgent)) {
                left += parent.clientLeft;
                top += parent.clientTop;
            }
            left += parent.offsetLeft;
            top += parent.offsetTop;
            parent = parent.offsetParent;
        }
        return {
            top,
            left
        };
    };